Device for assisting sheet conveying

摘要

The invention relates to a device for assisting sheet conveying by means of jets of compressed air in the region of the printing zone of the blanket cylinder and the impression cylinder in a printing unit which is not involved in printing, a printing gap being present between the blanket cylinder and the impression cylinder of a multicolour sheet-fed rotary printing machine. The object of the invention, to build up an air cushion between the sheet and the blanket cylinder for a printing unit which is not involved in printing whilst maintaining a smooth sheet run, is achieved in that known axially parallel blower pipes extending over the width of the cylinders are arranged ahead of and behind the printing zone, - the nozzles of the blower pipe ahead of the printing zone blowing a jet of compressed air against the blanket cylinder, - the nozzles of the blower pipe behind the printing zone blowing a jet of compressed air against the impression cylinder, - one nozzle of the blower pipe ahead of the printing zone being disposed in each case opposite a nozzle of the blower pipe behind the printing zone, and - in that the jets of compressed air contact the sheet and smooth it out counter to the direction of movement of the sheet. <IMAGE>